The AD7938/AD7939 are 12-bit and 10-bit, high speed, low power, successive approximation (SAR) analog-to-digital converters (ADCs). The parts operate from a single 2.7 V to 5.25 V power supply and feature throughput rates up to 1.5 MSPS. The parts contain a low noise, wide bandwidth, differential track-and-hold amplifier that can handle input frequencies up to 50 MHz.
The AD7938/AD7939 feature eight analog input channels with a channel sequencer that allows a preprogrammed selection of channels to be converted sequentially. These parts can operate with either single-ended, fully differential, or pseudo differential analog inputs.
The conversion process and data acquisition are controlled using standard control inputs that allow easy interfacing with microprocessors and DSPs. The input signal is sampled on the falling edge of CONVST and the conversion is also initiated at this point.
The AD7938/AD7939 have an accurate on-chip 2.5 V reference that can be used as the reference source for the analog-to-digital conversion. Alternatively, this pin can be overdriven to provide an external reference.
These parts use advanced design techniques to achieve very low power dissipation at high throughput rates. They also feature flexible power management options. An on-chip control register allows the user to set up different operating conditions, including analog input range and configuration, output coding, power management, and channel sequencing.
- High throughput with low power consumption.
- Eight analog inputs with a channel sequencer.
- Accurate on-chip 2.5 V reference.
- Single-ended, pseudo differential, or fully differential analog inputs that are software selectable.
- Single-supply operation with VDRIVE function. The VDRIVE function allows the parallel interface to connect directly to 3 V or 5 V processor systems independent of VDD.
- No pipeline delay.
- Accurate control of the sampling instant via a CONVST input and once-off conversion control.
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
The EVAL-AD7938CBZ is a fully featured evaluation kit for the AD7938. This board operates in stand alone mode or in conjunction with the Evaluation Controller board . When operated with the Evaluation Controller board, software is provided enabling the user to perform detailed analysis of the ADC's performance. This software includes the technical note describing the operation and set up of the evaluation board in standalone operation or when operated with the Evaluation Controller board.
Recommended External Voltage References
Designing Power Supplies for High Speed ADC
Maximize Performance When Driving Differential ADCs
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ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.